Postretirement Benefit Plans - Weighted-Average Assumptions Used To Determine Benefit Obligations (Detail)	Dec. 31, 2014	Dec. 31, 2013
United States [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	4.09%	4.87%
United Kingdom [Member]
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Discount rate	3.50%	4.60%

The interest rate used to adjust for the time value of money for the plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant